This invention relates to a connecting device suitable for connecting two vehicles in a towing relationship to each other. More particularly it relates to such a device which includes an electrical coupling arrangement.
Many different tow hitches for connecting a towing vehicle to a towed vehicle are known. One known tow hitch comprises a mating ball and socket arrangement, the ball formation being secured to the rear end of the towing vehicle and the socket formation being secured to the front end of the towed vehicle. In use the vehicles are connected to each other by inserting the ball formation in the socket formation and locking them in a sliding engagement. Another known tow hitch comprises a so-called fifth wheel arrangement.
It is also well known that with road going vehicles, the towed vehicle (for example a caravan or trailer) is required to have lights, such as tail lights, stop lights, indicator lights and the like. These lights are connected to the towing vehicle""s electrical system. When known tow hitches as described above are employed, a separate plug and socket arrangement with a plurality of contacts is provided for connecting the lights of the towed vehicle to the lights of the towing vehicle. A disadvantage of this system is that the user often forgets to connect the electrical system of the towed vehicle to that of the towing vehicle. These electrical connections are also prone to damage.
South African patent 96/1682 discloses a tow-hitch arrangement having two anchor arrangements one to be mounted to the towing vehicle and the other to the towed vehicle. The anchor arrangement includes complementary sliding contacts, which come into electrical contact with one another when the anchor arrangements are connected to each other. One disadvantage of this arrangement is that the anchor arrangements include a large number of parts to ensure that the contacts remain in contact with each other. Another disadvantage is that direct contact is established between the lights of the two vehicles, for example, the brake lights of the one vehicle is connected directly to the brake lights of the other vehicle etc. which may result in power drain which in turn may prevent the lights of the towed vehicle from being sufficiently illuminated. A further disadvantage is that many pairs of contacts have to be provided.
U.K. patent 789,655 discloses a coupling wherein a ball member of the coupling has a holding bolt through it, and insulated therefrom. The head of the bolt forms a portion of the periphery of the ball with a wide insulation between such head and ball.
U.S. Pat. No. 5,521,466 discloses an apparatus for actuating a plurality of operating lamps of a towed vehicle according to the operating fights of a towing vehicle. The apparatus includes an encoder and decoder arrangement for actuating the lights of the towed vehicle. This apparatus again has the disadvantage that a separate electrical coupling and tow hitch needs to be provided. Another disadvantage is that a number of electrical couplings need to be provided between the vehicles, at least one for the power line and at least one for the signals from the encoder to the decoder.
EP-A-0 692 396 discloses an electrical trailer connection device which includes one or more data network connections for connection to the data network of the tow vehicle. A control unit is provided which is capable of controlling a semiconductor power switch group in dependence on control information received via the data network connections. In this way only a few connections, e.g. three of four, to the tow vehicle are required which simplifies fitting and reduces the amount of cabling. Multiple connections between the tow vehicle and trailer is provided via the connection contact unit.
It is an object of the present invention to provide an alternative connecting device which overcomes or reduces at least some of the above disadvantages.
According to the present invention there is provided a connecting device suitable for connecting a towing vehicle with rear lights in a towing relationship to a towed vehicle with rear lights and for actuating the rear lights of the towed vehicle in accordance with the rear lights of the towing vehicle, the connecting device comprising a first coupling member connected or connectable to the towing vehicle; a second coupling member connected or connectable to the towed vehicle, which coupling members are lockingly engageable for connecting the vehicles in a towing relationship; a power supplyconductor for supplying power to the rear lights of the towed vehicle from a power supply on the towing vehicle; a pair of interengageable electrical contacts provided in the power supply conductor, the pair including a first contact provided on the first coupling member and a second contact provided on the second coupling member, the first and second contacts engaging each other when the first and second coupling members lockingly engage each other to allow power to flow through the pair of contacts; a signal transmitter arrangement for transmitting at least one control signal when power is supplied to at least one rear light of the towing vehicle to activate it; and a signal receiver arrangement for receiving the at least one control signal from the transmitter arrangement and activating at least one rear light of the towed vehicle in accordance with the at least one control signal received.
In this specification the terms xe2x80x9ctowxe2x80x9d or xe2x80x9ctowingxe2x80x9d relate to both pull and push arrangements.
The towing vehicle may be a vehicle which in turn is towed by another vehicle. Alternatively it may comprise a vehicle which includes a propelling means for propelling the vehicle. Preferably the vehicle comprises a road-going vehicle, for example a motor car, truck, light delivery vehicle or the like. The towed vehicle may comprise any suitable towed vehicle and may include a trailer, caravan or the like.
The rear lights on the towing and towed vehicle may include a number of lights selected from the group comprising one or more tail lights; one or more brake lights; one or more indicator lights; one or more reverse lights and a number plate light. Usually at least two tail lights, two brake lights and two indicator lights are provided at the rear ends of the vehicles.
The first and second coupling members may comprise a fifth wheel and pin arrangement, for example a conventional fifth wheel and pin arrangement. Alternatively the first and second coupling members may comprise a ball and socket arrangement, for example a conventional ball and socket arrangement.
The power supply conductor may comprise an electrical wire having a conductive core in an insulating cover. The power supply conductor may also provide power to other equipment on the towed vehicle such as a refrigerator.
A switch may be provided in the power supply conductor to regulate current flow through the power supply conductor, preferably regulating power supply to the first contact.
Preferably the pair of interengageable electrical contacts slidingly engage each other. Preferably at least one of the contacts include a biasing means for biasing the one contact onto the other. The biasing means may comprise a spring.
In a preferred embodiment of the invention the device includes only one pair of electrical contacts between the first and second coupling members through which the control and power signals pass. Additional earth contacts may be provided.
The signal transmitter arrangement may include an encoder receiving information of the status of the power supplied to the rear lights of the towing vehicle and the encoder in response thereto generating a signal carrying information corresponding to the status of the rear lights. The encoder may include as inputs lines connected to the power lines supplying power to the rear lights of the towing vehicle.
The encoder may comprise a microprocessor.
The signal generated by the encoder may carry information corresponding to the specific combination of the status of power supplied to the rear lights of the towing vehicle. For example, the signal may be responsive to which rear lights power is supplied. Alternatively or additionally it may be responsive to which rear lights power is not supplied.
The signal transmitter arrangement may transmit the at least one control signal via the air to the receiver. Preferably the at least one control signal is transmitted via a transmission line. A separate transmission line may be provided for transmitting the at least one control signal and suitable contacts (for example of the type in the power line) may be provided in the signal transmission line to establish contact in the line between the towing vehicle and the towed vehicle.
Preferably however the at least one control signal is transmitted via the power supply conductor to the signal receiver arrangement. The at least one control signal is preferably superimposed on the power signal in the power supply conductor, that is the power signal is modulated with said at least one control signal. Preferably the signal transmitter arrangement includes a timer arrangement for generating an oscillating control signal which is superimposed on the power signal.
The signal transmission arrangement may also include current amplification means for amplifying the control signal. The current amplifying means may comprise a transistor arrangement.
The signal receiver arrangement may include a decoder for decoding the control signal received from the transmitter and for controlling switches in power lines for supplying power to the rear lights of the towed vehicle, thereby to supply power to the said rear lights in accordance with the control signal received.
The signal receiver arrangement may include means for separating the control signal from the power signal. The separating means may comprise a filter arrangement and the filter arrangement may comprise a RC filter.
The signal receiver arrangement may also include means for amplifying the separated control signal. The amplifying means may comprise an op-amp circuit.
The decoder may comprise a microprocessor.
The signal receiver arrangement may include a current amplifying means for amplifying power output from the microprocessor. The current amplifying means may comprise transistor drivers.
The connecting device may also include a test arrangement whereby the signal transmitter arrangement is activated to send one or more control signals to activate the rear lights of the towing vehicle allowing the user to check whether they work. Preferably the rear lights may be activated one after the other and preferably in sequence.
The connecting device may also include a warning arrangement to provide a warning if the towed vehicle is connected to the towing vehicle but the contacts 17 and 18 do not allow power through.
According to another aspect of the present invention there is provided a first part of a connecting device which in use connects with a second part of a connecting device to connect a towing vehicle with rear lights in a towing relationship to a towed vehicle, the first part comprising a first coupling member connectable to a towing vehicle and being suitable to lockingly engage a second coupling member on a towed vehicle for connecting the vehicles in a towing relationship; a power supply conductor through which power can be supplied; a first electrical contact in the power supply conductor which contact is located on the a first coupling member in use to engage a second electrical contact on the second coupling member when the first and second coupling members lockingly engage each other; and a signal transmitter arrangement in use associated with rear fights of the towing vehicle for transmitting at least one control signal which signals to which rear lights of the towing vehicle power is supplied.
According to another aspect of the present invention there is provided a second part of a connecting device which in use connects with a first part of a connecting device to connect a towing vehicle with rear lights to a towed vehicle with rear lights in a towing relationship, the second part comprising a second coupling member connectable to a towed vehicle and being suitable to lockingly engage a first coupling member on a towing vehicle for connecting the vehicles in a towing relationship; a power supply conductor through which power can be supplied; a second electrical contact in the power supply conductor which contact is located on the second coupling member in use to engage a first electrical contact on the first coupling member when the first and second coupling members lockingly engage each other; and a signal receiver arrangement for receiving a control signal which signals to which rear lights of the towing vehicle power is supplied and the signal receiver arrangement in use activating at least one rear light of the towed vehicle in accordance with the control signal received.
According to another aspect of the present invention there is provided a vehicle equipped with the first part of a connecting device substantially as described hereinabove.
According to another aspect of the present invention there is provided a vehicle equipped with the second part of the connecting device substantially as described hereinabove.
According to another aspect of the present invention a coupling member suitable for lockingly engaging a mating coupling member to allow two vehicles to be connected to each other in a towing relationship comprises a ball formation on one end of a shank, an electrical contact provided on the ball formation and a conductor for supplying power to the contact extending at least partly through the ball formation.